Optical Performances of Solar Selective Coatings under Different Preparation Conditions

Solar energy is one kind of important resource for clean and renewable energy, and solar selective coatings have been widely used to reduce the heat loss of solar heat receiver. In present paper, solar selective coatings were made from Pyromark 2500 under different preparation conditions, and associated optical performances were measured by ultraviolet, visible, near-infrared spectrophotometers. As the preparation temperature increases, the coating surface apparently changed, and it became smooth with little brush trace and roughness with preparation temperature below 600°C, while it will crack at high temperature above 800°C. As the preparation temperature increases, the coating absorptivity only changed very little in the ultraviolet and visible wave range, while it will sharply decrease for about 20% in the near-infrared wave range. The coating thickness only had little effects on the coating reflectivity in the ultraviolet and visible wave range, and the absorptivity in the near-infrared wave range will be about 4% higher for thick enough coating.